Our laboratory investigates mechanisms of gene control in mammalian cells in culture and in the whole animal. One of two major projects, dealing with the E1A regulatory function of adenovirus, has been completed. The E1A function acts as a transcriptional modulator and is involved in malignant transformation. Sequences encoding E1A proteins or certain domains of these proteins have been inserted in prokaryotic expression vectors, and E1A proteins have been produced in E. coli. We microinjected the proteins into mammalian cells and measured their ability to migrate to the cell nucleus and to activate an adenovirus E1A deletion mutant. Information for nuclear localization and for viral gene activation has been shown to be encoded by distinct domains of the adenovirus E1A gene. Our second project involves insertion of specific gene constructs into mouse embryos. Spatial and temporal control of the expression of the inserted genes is examined in the resulting transgenic animals. So far, we have analyzed mice carrying three difference chimeric gene constructs. Each of these contains the gene for bacterial chloramphenicol acetyl transferase (CAT) under the control of a promoter/enhancer region derived from either the mouse Alpha2(I) collagen gene or from Rous sarcoma virus (RSV). The temporal and spatial contol of CAT expression in mice carrying the AlphaA crystallin-CAT or the Alpha2(I) collagen CAT construct reflects that of the genuine mouse genes from which the 5' flanking sequences of the chimeric genes were derived. In mice carrying the RSV-CAT construct CAT expression is preferentially directed to muscle and connective tissue. This reflects the disease specifically of sarcoma viruses. Finally, we have begun to analyze one RSV-CAT transgenic strain which is characterized by a dominant trait of embryonic lethality.